JP5136701B2 - Control device for an internal combustion engine with a supercharger - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine with a supercharger, and more particularly to a control device for an internal combustion engine provided with a variable nozzle vane supercharger.

  2. Description of the Related Art An internal combustion engine (hereinafter also referred to as an engine) mounted on a vehicle is equipped with a supercharger (hereinafter also referred to as a turbocharger) that uses exhaust energy. In general, a turbocharger connects a turbine wheel that is rotated by exhaust gas flowing through an engine exhaust passage, a compressor impeller that forcibly feeds air in the intake passage to a combustion chamber of the engine, and the turbine wheel and the compressor impeller. Connecting shaft. In the turbocharger having such a structure, the turbine wheel disposed in the exhaust passage is rotated by the energy of the exhaust gas, and the compressor impeller disposed in the intake passage is rotated accordingly, whereby the intake air is supercharged, and the engine Supercharged air is forced into the combustion chamber of each cylinder.

  As a turbocharger mounted on a vehicle, a variable nozzle vane type turbocharger capable of adjusting a supercharging pressure with respect to exhaust energy has become mainstream.

  The variable nozzle vane turbocharger is, for example, a variable nozzle vane mechanism (VN mechanism) that is disposed in an exhaust gas flow path of a turbine housing and has a plurality of nozzle vanes (also referred to as movable vanes) that can change the flow area of the exhaust gas flow path. ) And actuators (motor actuators) that apply displacement (rotation) to these nozzle vanes, etc., and change the opening area of the nozzle vanes to change the flow area (throat area) between adjacent nozzle vanes. Thus, the flow rate of the exhaust gas introduced toward the turbine wheel is adjusted (see, for example, Patent Documents 1 and 2). By adjusting the exhaust gas flow rate in this manner, the rotational speeds of the turbine wheel and the compressor impeller can be adjusted to adjust the pressure of the air introduced into the combustion chamber of the engine.

  And with such a variable nozzle vane type turbocharger, the degree of freedom of adjustment of the supercharging pressure in the exhaust energy is increased, so the torque response that leads to acceleration is improved, and it is compatible with output, fuel consumption (fuel consumption rate), and emissions. There are advantages such as improving the degree of freedom. Note that variable nozzle vane turbochargers are being adopted not only in diesel engines but also in gasoline engines.

JP 2009-299505 A JP 2003-129853 A JP 2009-281144 A

  When the variable nozzle vane mechanism is provided in the turbocharger, when the flow velocity of the exhaust gas passing through the nozzle vane increases, the turbulence of the exhaust gas occurs in the downstream of the nozzle vane. A typical exhaust gas turbulence is Rankine vortex. It has been found that Rankine vortex is generated at the rear end of the nozzle vane and becomes a pressure pulsation having a frequency component proportional to the flow rate of the exhaust gas. In other words, the vortex shedding frequency f of the Rankine vortex satisfies the relationship of the theoretical formula [f = St * U / D St: Strouhal number (constant), U: flow velocity, D: wake width] The pressure pulsation caused by the Rankine vortex has a frequency component proportional to the flow rate of the exhaust gas passing through the nozzle vane. And when the frequency of such pressure pulsations is amplified by the spatial resonance of the space in the turbine housing and the space in the exhaust pipe (turbine housing to exhaust gas passage of the catalyst), the frequency from the exhaust port through the vehicle exhaust pipe It becomes a discharge sound, and the abnormal noise becomes a problem.

  Here, in order to avoid the pressure pulsation problem as described above, even if it is attempted to control the frequency of the spatial resonance of the turbine housing and catalyst system, which is an amplification factor, it is difficult due to constraints such as supercharging efficiency, emission, and mounting requirements. Since the degree of freedom of design is low, it is difficult to suppress the generation of abnormal noise. Even if the frequency of the spatial resonance is changed, the pressure pulsation has a frequency component proportional to the flow rate of the exhaust gas as described above. Therefore, avoid the amplification (resonance) of the pulsation in the changed frequency band of the spatial resonance. I can't.

  Furthermore, although it is conceivable to add a sound absorbing structure to the vehicle exhaust pipe, the degree of freedom of measures for one abnormal noise phenomenon is low due to restrictions such as mounting requirements, appearance, and cost. Even if the vehicle measures are taken against the sound discharged from the vehicle exhaust pipe, the problem of the sound outside the vehicle (particularly, the problem of the generation of abnormal noise during racing (high-speed idling) while the vehicle is stopped) remains.

  For the reasons described above, measures on the upstream engine (turbocharger) side of the variable nozzle vane mechanism are required to suppress abnormal noise caused by pressure pulsation generated at the rear end of the nozzle vane. The current situation is not established.

  The present invention has been made in consideration of such circumstances, and in a control device for an internal combustion engine with a supercharger of a variable nozzle vane type, it is possible to suppress noise caused by pressure pulsation generated at the rear end of the nozzle vane. The purpose is to realize control.

  The present invention includes a throttle valve disposed in an intake passage, a compressor impeller provided in the intake passage, and a turbocharger having a turbine wheel provided in the exhaust passage, an exhaust passage upstream of the turbine wheel, An EGR valve that is provided in an EGR passage that connects an intake passage downstream of the compressor impeller and that adjusts the amount of exhaust gas that circulates from the exhaust passage to the intake passage; and a downstream side of the turbine housing of the turbocharger And a plurality of nozzle vanes provided on the outer peripheral side of the turbine wheel as the supercharger, and by changing the opening of the nozzle vanes, Control device for an internal combustion engine equipped with a variable nozzle vane supercharger with a variable nozzle vane mechanism for adjusting the flow It is based on the premise.

  In such a control device for an internal combustion engine with a supercharger, when accelerating or decelerating, the flow rate of exhaust gas passing through the nozzle vane is a space in the exhaust gas passage space from the turbine housing of the supercharger to the catalyst. The throttle valve opening, the EGR valve opening, the nozzle vane are adjusted so that the exhaust gas flowing through the nozzle vane has a flow velocity outside the spatial resonance region when reaching a flow velocity that enters the resonance region. The present invention is characterized in that it has a flow rate control means for adjusting the flow rate of the exhaust gas passing through the nozzle vane by adjusting any one or a plurality of the opening degrees.

  According to the present invention, the frequency of pressure pulsation generated at the rear end of the nozzle vane is proportional to the flow velocity of exhaust gas passing through the nozzle vane (flow velocity at the rear end of the nozzle vane). When the flow rate of exhaust gas passing through the nozzle vane (hereinafter also referred to as VN passage flow rate) reaches a flow rate that falls within the spatial resonance range, the VN passage flow rate is outside the spatial resonance range. VN passage flow velocity is changed by controlling one or more of the throttle valve opening, the EGR valve opening, and the nozzle vane opening so that the VN passage flow velocity is increased. Side or the side where the VN passage flow velocity is reduced), it is possible to pass through the spatial resonance region quickly. As a result, the time during which the frequency of the pressure pulsation generated at the rear end of the nozzle vane is amplified in the spatial resonance region can be shortened, and the generation of abnormal noise due to the pressure pulsation can be suppressed. In addition, since the VN passage flow velocity only needs to be changed for a short time while passing through the spatial resonance region during acceleration or deceleration, an abnormal noise caused by pressure pulsation while ensuring the required supercharging pressure (air amount). Can be suppressed.

  As a specific configuration of the present invention, the VN passage flow velocity is a parameter related to the flow rate of exhaust gas toward the turbine wheel (nozzle vane) of the turbocharger, which is a supercharging pressure (air amount), intake air temperature, fuel injection amount ( It is estimated based on the amount of combustion gas), the opening of the throttle valve, the opening of the EGR valve, and the opening of the nozzle vane. Then, when the estimated VN passage flow velocity reaches a flow velocity that enters the spatial resonance region, the opening of the throttle valve, the opening of the EGR valve, and the like so that the VN passage flow velocity becomes a flow velocity outside the spatial resonance region, A configuration in which any one or a plurality of nozzle vane openings is adjusted to change the VN passage flow velocity can be exemplified. Note that the fuel injection state (combustion gas amount) is treated as “0” because the fuel cut state occurs during deceleration (when the accelerator is OFF).

  Specific control of the present invention will be described below.

  First, during acceleration, when the VN passage flow velocity reaches a flow velocity that falls within the spatial resonance range (for example, the flow velocity vna at point A shown in FIG. 9), the throttle valve opening, the EGR valve opening, and the nozzle vane opening. To make the VN passage flow velocity larger than that during normal control (control to secure the target boost pressure). In this way, when reaching the spatial resonance region during acceleration, the flow velocity passing through the spatial resonance region (the flow velocity vnb at point B shown in FIG. 9) can be quickly increased by increasing the VN passage flow velocity than during normal control. Since it can transfer, it can pass through a spatial resonance area (A-B section shown in Drawing 9) in a short time.

  In this case, after setting the opening degree of the EGR valve to a predetermined value on the closing side, the VN passage flow rate is increased by controlling the opening degree of the nozzle vane to the closing side. Specifically, the opening of the EGR valve is set to the smallest possible value (opening on the closing side) within a range where appropriate emissions can be ensured, and the opening of the nozzle vane is taken into consideration for drivability, etc. Thus, by setting the value as close as possible, the VN passage flow velocity is made larger than that during normal control. If such a setting is made, the spatial resonance region can be passed in a short time during acceleration without causing a reduction in emission and drivability.

  Here, at the time of acceleration, as described above, if the opening degree of the EGR valve and the opening degree of the nozzle vane are set to the closed side, the supercharging pressure may become excessive due to an increase in the turbo rotational speed. In consideration of this point, while the VN passage flow rate is the flow rate in the spatial resonance region, the opening of the throttle valve is adjusted (adjusted to the closed side) to limit (guard) the excessive increase in the supercharging pressure. May be.

  In addition, as a specific control during acceleration, the VN passage flow velocity is normally controlled (a target supercharging pressure is ensured) until a predetermined time elapses after the VN passage velocity reaches a flow velocity that enters the spatial resonance region. The control of continuing the control to be larger than the control time and returning to the normal control when a predetermined time elapses can be mentioned.

  The predetermined time is a time required for passing through the spatial resonance region (passing through the sections A to B of the spatial resonance region Ra shown in FIG. 9) when the VN passage flow velocity during acceleration is larger than that during normal control. Therefore, a suitable value is set by experiment / simulation. With such a setting, since normal control can be returned after passing through the spatial resonance region, occurrence of abnormal noise due to pressure pulsation can be reliably suppressed.

  In addition, it is possible to determine that the control has passed through the spatial resonance region by managing the timing at which the control for increasing the VN passage flow velocity is completed in this way, that is, the timing for returning to the normal control after passing through the spatial resonance region. The opening degree of the EGR valve, the opening degree of the nozzle vane, etc. can be returned to the opening degree of the normal control.

  Next, specific control during deceleration will be described.

  First, at the time of deceleration, when the VN passage flow velocity reaches a flow velocity that falls within the spatial resonance range (for example, the flow velocity vnb at point B shown in FIG. 9), the throttle valve opening, the EGR valve opening, and the nozzle vane opening. The VN passage flow velocity is controlled to be smaller than that during normal control (control to ensure the target boost pressure) by controlling any one or a plurality of opening degrees. In this way, when the vehicle reaches the spatial resonance region during deceleration, the flow velocity passing through the spatial resonance region (flow velocity vna at point A shown in FIG. 9) can be quickly increased by making the VN passage flow velocity smaller than that during normal control. Since it can transfer, it can pass through a spatial resonance area (B-A section shown in Drawing 9) in a short time.

  In this case, after setting the opening degree of the EGR valve to a predetermined value on the opening side, the VN passage flow velocity is reduced by controlling the opening degree of the nozzle vane to the opening side. Specifically, the opening of the EGR valve is set to the largest possible value (opening opening) within a range that can ensure appropriate emissions, and the opening of the nozzle vane is taken into consideration for drivability and other factors. Thus, by setting the open side value as much as possible, the VN passage flow velocity is made smaller than that during normal control. If such a setting is made, it will be possible to pass through the spatial resonance region in a short time without deteriorating emissions and drivability.

  Further, as a specific control at the time of deceleration, the VN passage flow velocity is normally controlled (a target supercharging pressure is ensured) until a predetermined time elapses after the VN passage flow velocity reaches the flow velocity entering the spatial resonance region. Control that is smaller than that at the time of control), and the control is returned to the normal control when a predetermined time elapses.

  The predetermined time is a time required for passing through the spatial resonance region (passing through the sections B to A of the spatial resonance region Ra shown in FIG. 9) when the VN passage flow velocity is smaller than during normal control during deceleration. Therefore, a suitable value is set by experiment / simulation. With such a setting, since normal control can be returned after passing through the spatial resonance region, occurrence of abnormal noise due to pressure pulsation can be reliably suppressed.

  Further, in this way, the time when the control for reducing the VN passage flow velocity is completed at the time of deceleration, that is, the timing for returning to the normal control after passing through the spatial resonance region is managed by the time, so that the vehicle has passed through the spatial resonance region. Without determining this, the EGR valve opening, the nozzle vane opening, and the like can be returned to normal control.

  As another specific means of the present invention, when accelerating or decelerating (when the internal combustion engine is accelerating or decelerating), the frequency of pressure pulsation proportional to the flow rate of exhaust gas passing through the nozzle vane (VN passing flow rate) is: When reaching a frequency that enters the spatial resonance region in the exhaust gas passage space from the turbine housing of the turbocharger to the catalyst, the opening degree of the throttle valve and the EGR valve are adjusted so that the pressure pulsation frequency deviates from the spatial resonance region. A configuration in which any one or more of the opening degree and the opening degree of the nozzle vane is adjusted to control the flow rate of the exhaust gas passing through the nozzle vane can be mentioned.

  Even in such control, the spatial resonance region can be quickly passed during acceleration or deceleration. As a result, the time during which the frequency of the pressure pulsation generated at the rear end of the nozzle vane is amplified in the spatial resonance region can be shortened, and the generation of abnormal noise due to the pressure pulsation can be suppressed. In addition, since the VN passage flow velocity only needs to be changed for a short time while passing through the spatial resonance region during acceleration or deceleration, an abnormal noise caused by pressure pulsation while ensuring the required supercharging pressure (air amount). Can be suppressed.

  Here, in this control as well as the control described above, when the frequency of pressure pulsation reaches a frequency that enters the spatial resonance region during acceleration, the opening degree of the EGR valve is set to a predetermined value on the closing side. Thus, the control is performed such that the VN passage flow velocity is made larger than that in the normal control by controlling the opening degree of the nozzle vane to the closing side. In addition, when the frequency of pressure pulsation reaches a frequency that enters the spatial resonance region during deceleration, the opening degree of the EGR valve is set to a predetermined value on the opening side, and then the opening degree of the nozzle vane is controlled to the opening side. Control is performed to make the VN passage flow velocity smaller than that during normal control.

  In this control, the control when reaching the spatial resonance region at the time of acceleration or deceleration, for example, the control of the opening of the throttle valve, the opening of the EGR valve, the opening of the nozzle vane, etc. Techniques can be applied.

  As another specific means of the present invention, a turbocharger having a throttle valve disposed in the intake passage, a compressor impeller provided in the intake passage, and a turbine wheel provided in the exhaust passage, And a catalyst provided in an exhaust passage on the downstream side of the turbine housing, and has a plurality of nozzle vanes provided on the outer peripheral side of the turbine wheel as the supercharger, and changes the opening degree of the nozzle vanes. In the control device for an internal combustion engine equipped with a variable nozzle vane supercharger having a variable nozzle vane mechanism that adjusts the flow of exhaust gas by the above, at the time of acceleration or deceleration (at the time of acceleration or deceleration of the internal combustion engine), The flow rate of the exhaust gas passing through the nozzle vanes is such that the exhaust gas passage space from the turbine housing of the turbocharger to the catalyst is empty. When the flow velocity that enters the resonance region is reached, either the opening degree of the throttle valve or the opening amount of the nozzle vane so that the flow velocity of the exhaust gas passing through the nozzle vane becomes a flow velocity outside the spatial resonance region. Or the structure of adjusting the opening degree of both and controlling the flow velocity of the exhaust gas which passes the said nozzle vane can be mentioned.

  Even in such control, the spatial resonance region can be quickly passed during acceleration or deceleration. As a result, the time during which the frequency of the pressure pulsation generated at the rear end of the nozzle vane is amplified in the spatial resonance region can be shortened, and the generation of abnormal noise due to the pressure pulsation can be suppressed. In addition, since the VN passage flow velocity only needs to be changed for a short time while passing through the spatial resonance region during acceleration or deceleration, an abnormal noise caused by pressure pulsation while ensuring the required supercharging pressure (air amount). Can be suppressed.

  Further, as other specific means, a turbo valve having a throttle valve arranged in the intake passage, a compressor impeller provided in the intake passage and a turbine wheel provided in the exhaust passage, and a turbine of the supercharger And a catalyst provided in an exhaust passage on the downstream side of the housing, and has a plurality of nozzle vanes provided on the outer peripheral side of the turbine wheel as the supercharger, and changing the opening degree of the nozzle vanes. In a control device for an internal combustion engine equipped with a variable nozzle vane type supercharger equipped with a variable nozzle vane mechanism that adjusts the flow of exhaust gas by means of a nozzle vane during acceleration or deceleration (acceleration or deceleration of the internal combustion engine) The frequency of pressure pulsation proportional to the flow rate of exhaust gas passing through (VN flow rate) is reduced from the turbocharger turbine housing to the catalyst. One of the opening degree of the throttle valve and the opening degree of the nozzle vane so that the pressure pulsation frequency deviates from the spatial resonance area when reaching the frequency that enters the spatial resonance area in the exhaust gas passage space at A configuration in which the flow rate of the exhaust gas passing through the nozzle vanes is controlled by adjusting both opening degrees can be mentioned.

  Even in such control, the spatial resonance region can be quickly passed during acceleration or deceleration. As a result, the time during which the frequency of the pressure pulsation generated at the rear end of the nozzle vane is amplified in the spatial resonance region can be shortened, and the generation of abnormal noise due to the pressure pulsation can be suppressed. In addition, since the VN passage flow velocity only needs to be changed for a short time while passing through the spatial resonance region during acceleration or deceleration, an abnormal noise caused by pressure pulsation while ensuring the required supercharging pressure (air amount). Can be suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of the noise resulting from a pressure pulsation can be suppressed by control by the side of an internal combustion engine (supercharger).

It is a schematic structure figure showing an example of a diesel engine to which the present invention is applied. It is a longitudinal cross-sectional view which shows an example of the turbocharger with which an engine is equipped. It is the figure which looked at the variable nozzle vane mechanism from the outside of the turbocharger. FIG. 3 shows a state in which the nozzle vane is on the open side. It is the figure which looked at the variable nozzle vane mechanism from the inside of a turbocharger. FIG. 4 shows a state where the nozzle vane is on the open side. It is the figure which looked at the variable nozzle vane mechanism from the outside of the turbocharger. FIG. 5 shows a state in which the nozzle vane is on the closed side. It is the figure which looked at the variable nozzle vane mechanism from the inside of a turbocharger. FIG. 6 shows a state where the nozzle vane is on the closed side. It is a block diagram which shows the structure of control systems, such as ECU. It is a figure which shows typically the flow of the exhaust gas which passes a nozzle vane. It is a figure which shows typically the pressure pulsation and spatial resonance area which generate | occur | produce at the nozzle vane rear end. It is a flowchart which shows an example of the VN passage flow velocity control at the time of acceleration. It is a flowchart which shows an example of the VN passage flow velocity control at the time of deceleration. It is a figure which shows an example of the map which calculates an EGR valve opening degree (at the time of acceleration). It is a figure which shows an example of the map which calculates an EGR valve opening degree (at the time of deceleration).

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

-Engine-
A schematic configuration of an engine (internal combustion engine) to which the present invention is applied will be described with reference to FIG. FIG. 1 shows only the configuration of one cylinder of the engine.

  An engine 1 shown in FIG. 1 is an in-cylinder direct injection four-cylinder diesel engine, and a piston 1c that reciprocates in the vertical direction is provided in a cylinder block 1a constituting each cylinder. The piston 1c is connected to the crankshaft 15 via the connecting rod 16, and the reciprocating motion of the piston 1c is converted into rotation of the crankshaft 15 by the connecting rod 16. The crankshaft 15 of the engine 1 is connected to a transmission (not shown), and can transmit power from the engine 1 to drive wheels (not shown) of the vehicle via the transmission.

  A signal rotor 17 is attached to the crankshaft 15. A plurality of protrusions (teeth) 17a... 17a are provided on the outer peripheral surface of the signal rotor 17 at equal angles. An engine speed sensor (crank position sensor) 25 is disposed near the side of the signal rotor 17. The engine speed sensor 25 is, for example, an electromagnetic pickup, and generates a pulsed signal (output pulse) corresponding to the protrusion 17a of the signal rotor 17 when the crankshaft 15 rotates.

  The cylinder block 1a of the engine 1 is provided with a water temperature sensor 21 that detects the engine cooling water temperature. A cylinder head 1b is provided at the upper end of the cylinder block 1a, and a combustion chamber 1d is formed between the cylinder head 1b and the piston 1c.

  An oil pan 18 for storing engine oil is provided below the cylinder block 1a of the engine 1. The engine oil stored in the oil pan 18 is pumped up by an oil pump through an oil strainer that removes foreign matters during operation of the engine 1 and further purified by an oil filter, and then the piston 1c, the crankshaft 15, and the connecting oil. It is supplied to the rod 16 and used for lubrication and cooling of each part.

  The cylinder head 1 b of the engine 1 is provided with an injector 2 for directly injecting fuel into the combustion chamber 1 d of the engine 1. A common rail (accumulation chamber) 3 is connected to the injector 2, and fuel in the common rail 3 is injected from the injector 2 into the combustion chamber 1 d while the injector 2 is open.

  The common rail 3 is provided with a rail pressure sensor 24 for detecting the pressure (rail pressure) of the high-pressure fuel in the common rail 3. A supply pump 4 that is a fuel pump is connected to the common rail 3.

  The supply pump 4 is driven by the rotational force of the crankshaft 15 of the engine 1. By driving the supply pump 4, fuel is supplied from the fuel tank 40 to the common rail 3, and the injector 2 is opened at a predetermined timing, whereby the fuel is injected into the combustion chamber 1 d of each cylinder of the engine 1. The injected fuel is combusted in the combustion chamber 1d and exhausted as exhaust gas. The valve opening timing (injection period) of the injector 2 is controlled by an ECU (Electronic Control Unit) 200 described later.

  An intake passage 11 and an exhaust passage 12 are connected to the combustion chamber 1 d of the engine 1. An intake valve 13 is provided between the intake passage 11 and the combustion chamber 1d. By opening and closing the intake valve 13, the intake passage 11 and the combustion chamber 1d are communicated or blocked.

  Further, an exhaust valve 14 is provided between the exhaust passage 12 and the combustion chamber 1d. By opening and closing the exhaust valve 14, the exhaust passage 12 and the combustion chamber 1d are communicated or blocked. The opening / closing drive of the intake valve 13 and the exhaust valve 14 is performed by each rotation of the intake camshaft and the exhaust camshaft to which the rotation of the crankshaft 15 is transmitted.

  In the intake passage 11, an air cleaner (not shown), an air flow meter 22 for detecting an intake air amount (new air amount), a compressor impeller 112 of a turbocharger 100 to be described later, and the intake increased in temperature by supercharging in the turbocharger 100. An intercooler 7 for forcibly cooling air, an intake air temperature sensor 23, a throttle valve 6 and an intake manifold pressure sensor (supercharge pressure sensor) 28 for detecting the pressure (supercharge pressure) in the intake manifold 11a are arranged. ing.

  The throttle valve 6 is disposed in the intake passage 11 on the downstream side (downstream side of the intake air flow) of the intercooler 7 (compressor impeller 102 of the turbocharger 100). The throttle valve 6 is an electronically controlled valve whose opening is adjusted by a throttle motor 60. The opening of the throttle valve 6 (throttle opening) is detected by a throttle opening sensor 26. The throttle valve 6 of this example can electronically control the throttle opening independently of the driver's accelerator pedal operation.

  A front-stage S / C catalyst (start catalyst) 81 and a rear-stage U / F catalyst (underfloor catalyst) 82 are arranged in the exhaust passage 12. The S / C catalyst 81 is constituted by, for example, a three-way catalyst that can purify hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NOx), and the like. Further, the U / F catalyst 82 is constituted by, for example, a NOx catalyst (for example, NSR (NOx Storage Reduction) catalyst) having a function of storing NOx in exhaust gas and reducing the stored NOx.

-Turbocharger-
The engine 1 is equipped with a turbocharger (supercharger) 100 that supercharges intake air using exhaust pressure.

  As shown in FIGS. 1 and 2, the turbocharger 100 includes a turbine wheel 101 disposed in the exhaust passage 12, a compressor impeller 102 disposed in the intake passage 11, and the turbine wheel 101 and the compressor impeller 102 integrated with each other. The turbine wheel 101 disposed in the exhaust passage 12 is rotated by exhaust energy, and the compressor impeller 102 disposed in the intake passage 11 is rotated accordingly. Then, the intake air is supercharged by the rotation of the compressor impeller 102, and the supercharged air is forcibly sent into the combustion chamber of each cylinder of the engine 1.

  The turbine wheel 101 is accommodated in the turbine housing 111, and the compressor impeller 102 is accommodated in the compressor housing 112. The floating bearings 104 and 104 that support the connecting shaft 103 are accommodated in a center housing 113, and the turbine housing 111 and the compressor housing 112 are attached to both sides of the center housing 113.

  The turbocharger 100 of this example is a variable nozzle type turbocharger (VNT), and a variable nozzle vane mechanism 120 is provided on the turbine wheel 101 side, and the opening degree of the variable nozzle vane mechanism 120 (hereinafter referred to as VN opening degree). The supercharging pressure of the engine 1 can be adjusted. Details of the variable nozzle vane mechanism 120 will be described later.

-EGR device-
Further, the engine 1 is equipped with an EGR device 5. The EGR device 5 is a device that reduces the combustion temperature in the combustion chamber 1d and reduces the amount of NOx generated by introducing a part of the exhaust gas into the intake air.

  As shown in FIG. 1, the EGR device 5 includes an exhaust passage 12 upstream of the turbine wheel 101 of the turbocharger 100 (upstream of the exhaust gas flow) and a downstream of the intercooler 7 (compressor impeller 102 of the turbocharger 100). An EGR passage 51 communicating with the intake passage 11 on the side (downstream of the intake air flow), an EGR catalyst (for example, an oxidation catalyst) 52 provided in the EGR passage 51, an EGR cooler 53, an EGR valve 54, and the like It is configured. In the EGR device 5 having such a configuration, the EGR rate [EGR amount / (EGR amount + intake air amount (new air amount)) (%)] is changed by adjusting the opening degree of the EGR valve 54. The EGR amount (exhaust gas recirculation amount) introduced from the exhaust passage 12 to the intake passage 11 can be adjusted.

  The EGR device 5 may be provided with an EGR bypass passage that bypasses the EGR cooler 53 and an EGR bypass switching valve.

-Variable nozzle vane mechanism Next, the variable nozzle vane mechanism 120 of the turbocharger 100 will be described with reference to FIGS.

  The variable nozzle vane mechanism 120 of this example is disposed in a link chamber 114 formed between the turbine housing 111 and the center housing 113 of the turbocharger 100.

  The variable nozzle vane mechanism 120 includes an annular unison ring 122, a plurality of opening / closing arms 123, 123 that are located on the inner peripheral side of the unison ring 122 and that partially engage with the unison ring 122, and each of the opening / closing arms 123. A main arm 124 for driving each of the open / close arms, a vane shaft 125 for driving each nozzle vane 121, and a nozzle plate 126 for holding each vane shaft 125.

  The variable nozzle vane mechanism 120 is a mechanism for adjusting the rotation angle (rotation posture) of a plurality (for example, 12) of nozzle vanes 121... 121 arranged at equal intervals. The plurality of nozzle vanes 121... 121 are arranged on the outer peripheral side of the turbine wheel 101. Each nozzle vane 121 is disposed on a nozzle plate 126 and can be rotated by a predetermined angle about the vane shaft 125.

  The variable nozzle vane mechanism 120 rotates the drive link 127 connected to the main arm 124 by a predetermined angle, so that the turning force is transmitted to each nozzle vane 121 via the main arm 124, the unison ring 122, and each opening / closing arm 123. Then, each nozzle vane 121 rotates in conjunction with it.

  Specifically, the drive link 127 is rotatable around the drive shaft 128. The drive shaft 128 is pivotally connected to the drive link 127 and the main arm 124. Then, when the drive shaft 128 rotates as the drive link 127 rotates, this turning power is transmitted to the main arm 124. The inner peripheral end of the main arm 124 is fixed to the drive shaft 128. The outer peripheral side end of the main arm 124 is engaged with the unison ring 122, and when the main arm 124 rotates about the drive shaft 128, the turning force is transmitted to the unison ring 122.

  The outer peripheral side end of each open / close arm 123 is fitted to the inner peripheral surface of the unison ring 122, and when the unison ring 122 rotates, this turning force is transmitted to each open / close arm 123. Specifically, the unison ring 122 is disposed so as to be slidable in the circumferential direction with respect to the nozzle plate 126, and the main arm 124 and each of the plurality of recesses 122 a provided on the inner peripheral edge of the unison ring 122 are provided. The end portions on the outer peripheral side of the open / close arm 123 are fitted together, and the rotational force of the unison ring 122 is transmitted to each open / close arm 123.

  The nozzle plate 126 is fixed to the turbine housing 111. A pin 126a (see FIGS. 3 and 5) is inserted into the nozzle plate 126, and a roller 126b is fitted into the pin 126a. The roller 126b guides the inner peripheral surface of the unison ring 122. Accordingly, the unison ring 122 is held by the roller 126b and can be rotated in a predetermined direction.

  Each open / close arm 123 is rotatable about a vane shaft 125. Each vane shaft 125 is rotatably supported by the nozzle plate 126, and the open / close arm 123 and the nozzle vane 121 are connected to each other by the vane shaft 125 so as to rotate together. When each open / close arm 123 rotates as the unison ring 122 rotates, this rotation is transmitted to each vane shaft 125. Accordingly, each nozzle vane 121 rotates together with the vane shaft 125 and the opening / closing arm 123.

  A turbine housing vortex chamber 111a is provided in the turbine housing 111 that accommodates the turbine wheel 101. Exhaust gas is supplied to the turbine housing vortex chamber 111a, and the turbine wheel 101 is driven by the flow of the exhaust gas. At this time, as described above, the rotational position of each nozzle vane 121 is adjusted, and the rotational angle is set to adjust the flow rate and flow velocity of the exhaust from the turbine housing vortex chamber 111a to the turbine wheel 101. Can do. This makes it possible to adjust the supercharging performance. For example, the rotational position (displacement) of each nozzle vane 121 so as to reduce the flow path area (throat area) between the nozzle vanes 121 when the engine 1 rotates at a low speed. Is adjusted, the flow rate of the exhaust gas increases, and a high boost pressure can be obtained from the engine low speed range.

  The drive link 127 of the variable nozzle vane mechanism 120 is connected to the rod 129. The rod 129 is a rod-shaped member and is connected to the VN actuator 140. The VN actuator 140 includes an electric motor (DC motor) 141 and a conversion mechanism (for example, a worm gear and a gear mechanism having a worm wheel meshing with the worm gear) that converts the rotation of the electric motor 141 into a linear motion and transmits it to the rod 129. Etc .: not shown).

  The VN actuator 140 is driven and controlled by the ECU 200. The ECU 200 performs energization control of the electric motor 141 according to, for example, a nozzle vane opening request value required from the engine operating state. The electric motor 141 is supplied with electric power from an in-vehicle battery (not shown).

  Then, when the electric motor 141 rotates by energization control (rotational driving) of the electric motor 141, the rotational force is transmitted to the rod 129 through the rotating mechanism, and is driven along with the movement (forward / reverse) of the rod 129. As the link 127 rotates, each nozzle vane 121 rotates (displaces).

  Specifically, as shown in FIG. 3, when the rod 129 is pulled in the direction of the arrow X1 in the drawing (retraction of the rod 129), the unison ring 122 rotates in the direction of the arrow Y1 in the drawing, as shown in FIG. Further, each nozzle vane 121 rotates about the vane shaft 125 in the counterclockwise direction (Y1 direction) in the figure, and the nozzle vane opening (VN opening) is set large.

  On the other hand, as shown in FIG. 5, by pushing the rod 129 in the direction of the arrow X2 (advance of the rod 129), the unison ring 122 rotates in the direction of the arrow Y2 in the figure, and as shown in FIG. The nozzle vane 121 rotates about the vane shaft 125 in the clockwise direction (Y2 direction) in the figure, and the nozzle vane opening (VN opening) is set small.

  The ECU 200 controls the components such as the engine 1, the VN actuator 140 (electric motor 141) of the turbocharger 100, the throttle motor 60 that opens and closes the throttle valve 6, and the EGR valve 54.

-ECU-
As shown in FIG. 7, the ECU 200 includes a CPU 201, a ROM 202, a RAM 203, a backup RAM 204, and the like.

  The ROM 202 stores various control programs, maps that are referred to when the various control programs are executed, and the like. The CPU 201 executes various arithmetic processes based on various control programs and maps stored in the ROM 202. The RAM 203 is a memory that temporarily stores calculation results of the CPU 201, data input from each sensor, and the backup RAM 204 is a nonvolatile memory that stores data to be saved when the engine 1 is stopped, for example. Memory.

  The CPU 201, the ROM 202, the RAM 203, and the backup RAM 204 are connected to each other via the bus 207, and are connected to the input interface 205 and the output interface 206.

  The input interface 205 includes a water temperature sensor 21, an air flow meter 22, an intake air temperature sensor 23, a rail pressure sensor 24, an engine speed sensor 25, a throttle opening sensor 26 that detects the opening of the throttle valve 6, and an accelerator pedal depression amount. An accelerator opening sensor 27 for detecting (accelerator opening), an intake manifold pressure sensor (supercharging pressure sensor) 28, a vehicle speed sensor 29, and the like are connected.

  Connected to the output interface 206 are the injector 2, the throttle motor 60 of the throttle valve 6, the EGR valve 54, the VN actuator 140 (electric motor 141) for adjusting the opening of the variable nozzle vane mechanism 120 of the turbocharger 100, and the like. Yes.

  The ECU 200 controls the engine 1 including the opening control of the throttle valve 6 of the engine 1, fuel injection amount / injection timing control (injector 2 opening / closing control), EGR control, and the like based on the output signals of the various sensors described above. Perform various controls. Further, the ECU 200 executes the following “VN passage flow rate control”.

  The control device for the supercharged engine (internal combustion engine) of the present invention is realized by the program executed by the ECU 200 described above.

-Control of VN flow velocity-
First, the flow rate of exhaust gas passing through the nozzle vane 121 (VN passage flow rate) will be described.

  When the variable nozzle vane mechanism 120 is provided in the turbocharger 100, the exhaust gas flows through the nozzle vane 121 toward the turbine wheel 101 as shown in FIG. As described above, when the flow rate of the exhaust gas passing through the nozzle vane 121 increases, the turbulence of the exhaust gas occurs in the downstream of the nozzle vane 121. A typical exhaust gas turbulence is Rankine vortex.

  It has been found that Rankine vortices are generated at the rear end of the nozzle vane and have pressure pulsations having a frequency component proportional to the exhaust gas flow velocity. In other words, the vortex shedding frequency f of the Rankine vortex satisfies the relationship of the theoretical formula [f = St * U / D St: Strouhal number (constant), U: flow velocity, D: wake width] The pressure pulsation generated by the Rankine vortex has a frequency component proportional to the flow rate of exhaust gas passing through the nozzle vane 121 (flow rate at the rear end of the nozzle vane). Then, when the frequency of such pressure pulsation is amplified by the spatial resonance of the space in the turbine housing 111 and the space in the exhaust pipe 12a (turbine housing to catalyst exhaust gas passage), the exhaust port passes through the vehicle exhaust pipe. It becomes a discharge sound from, and the abnormal noise becomes a problem.

  Note that the proportionality between the frequency of the pressure pulsation generated at the rear end of the nozzle vane 121 and the VN passage flow velocity can be confirmed by experiments and simulations of the inventors of the present invention.

  Specifically, in the turbocharger (VNT) 100 including the variable nozzle vane mechanism 120 shown in FIGS. 2 to 6, assuming that the turbo rotation speed is the same (the gas flow rate to the turbine wheel 101 is the same) [Sample S1: VN When the opening is set to a certain opening value] and [Sample S2: VN opening is changed with respect to [Sample S1] above, and the passage area (throat area) between nozzle vanes is set to 1/2 When the frequency of the pressure pulsation generated at the rear end of the nozzle vane 121 is investigated (measured), the frequency in the case of [Sample S2] is The frequency of the pressure pulsation is approximately twice the frequency in the case of [Sample S1], that is, the flow rate of exhaust gas passing through the nozzle vane (flow velocity at the rear end of the nozzle vane). It was confirmed that the proportional.

  In this example, in consideration of the above-described problems, the VN passage flow velocity is used during acceleration or deceleration using the point that the frequency of the pressure pulsation generated at the rear end of the nozzle vane is proportional to the VN passage flow velocity. However, when reaching a flow velocity that enters the spatial resonance region (see FIG. 9) in the exhaust gas passage space from the turbine housing 111 to the S / C catalyst 81, the VN passage flow velocity becomes a flow velocity outside the spatial resonance region. As described above, the VN passage flow rate is controlled by adjusting the opening of the throttle valve 6 (hereinafter also referred to as the throttle opening), the opening of the EGR valve 54 (hereinafter also referred to as the EGR valve opening), and the VN opening. Therefore, it is a technical feature to suppress abnormal noise caused by pressure pulsation generated at the rear end of the nozzle vane 121.

  A specific example of the VN passage flow rate control will be described below.

<Spatial resonance area>
The spatial resonance area used for the VN passage flow velocity control in this example will be described.

  First, using CAE (Computer Aided Engineering), for the target engine 1, the space shape inside the turbine housing 111 of the turbocharger 100 and the exhaust pipe 12 a from the outlet of the turbine housing 111 to the S / C catalyst 81. A space shape of [turbine housing to catalyst] is specified by specifying a space shape (including a part of the space in the casing 81b of the S / C catalyst 81 (including the space from the inlet of the casing 81b to the catalyst main body 81a: see FIG. 1)). Resonance is evaluated to determine the resonance frequency. Based on the result, the spatial resonance area Ra shown in FIG. 9 is specified. Here, the frequency band (A to B section) of the spatial resonance area Ra takes into consideration the frequency area that is felt as an abnormal sound when the pressure pulsation frequency generated at the rear end of the nozzle vane 121 is amplified by the spatial resonance. The range is empirically adapted (for example, 600 Hz to 1 kHz).

  Then, the flow velocity value (the flow velocity vna at the point A) on the lower limit side (frequency side) of the spatial resonance area Ra thus identified, and the flow velocity value on the upper limit side (high frequency side) of the spatial resonance area Ra (high frequency side) The flow velocity vnb) at point B is obtained. Specifically, using the lower limit frequency (for example, 600 Hz) of the spatial resonance area Ra, the above-described theoretical formula of Rankine vortex [f = St * U / D St: Strouhal number (constant), U: flow velocity, D: The flow velocity vna at point A is calculated from the width of the wake. Similarly, the flow velocity vnb at point B is calculated from the theoretical formula of Rankine vortex using the upper limit frequency (for example, 1 kHz) of the spatial resonance area Ra. The flow velocity vna at point A and the flow velocity vnb at point B are stored in the ROM 202 of the ECU 200.

  In addition, about the said spatial resonance area Ra, you may make it specify the spatial resonance area Ra by acquiring the frequency of the spatial resonance of [turbine housing-catalyst] by the experiment etc. which used the actual engine.

<VN passage flow rate control during acceleration>
Next, the VN passage flow rate control during acceleration will be described with reference to the flowchart of FIG. The control routine of FIG. 10 is repeatedly executed in the ECU 200 every predetermined time (for example, every several msec).

  First, in step ST101, it is determined whether or not the engine 1 is accelerating. If the determination result is negative (NO), the process returns. If the determination result in step ST101 is affirmative (YES) (when acceleration is in progress), the process proceeds to step ST102.

  The determination as to whether or not the engine 1 is accelerating is performed, for example, when the accelerator pedal is depressed and the accelerator opening detected by the accelerator opening sensor 27 is greater than or equal to a predetermined value while the vehicle is running. What is necessary is just to determine that it is "at the time of acceleration" (or when the rate of change (increase rate) of the accelerator opening becomes a predetermined value or more).

  In step ST102, the flow velocity vna (the flow velocity at point A in FIG. 9) on the lower limit side of the spatial resonance area Ra described above is read.

  Next, the VN passage flow velocity is estimated in step ST103. Specifically, the parameters relating to the flow rate of exhaust gas toward the turbine wheel 101 (nozzle vane 121) of the turbocharger 100 are the supercharging pressure (air amount), intake air temperature, fuel injection amount (combustion gas amount), throttle. Based on the opening degree, the EGR valve opening degree, and the VN opening degree, the VN passage flow velocity is estimated using an estimation map previously adapted by experiments and simulations. Here, among the parameters used for VN passage flow velocity estimation, the supercharging pressure and the intake air temperature are calculated from the output signals of the intake manifold pressure sensor (supercharging pressure sensor) 28 and the intake air temperature sensor 23, respectively. Further, the fuel injection amount, the throttle opening, the EGR valve opening, and the VN opening are all obtained from the command value (required value).

  The VN passage flow velocity estimation process in step ST103 is repeatedly executed at predetermined time intervals (for example, every several milliseconds) until the determination result in step ST104 is affirmative (YES). That is, the estimated value of the VN passage flow velocity is sequentially updated.

  Next, in step ST104, it is determined whether or not the estimated VN passage flow velocity estimated in step ST103 has reached the lower limit flow velocity vna (the flow velocity at point A in FIG. 9) of the spatial resonance region Ra. If the determination result is negative (NO), normal control is continued (step ST108). Here, the normal control is a control for ensuring the target boost pressure (air amount), for example, based on the current operating state of the engine 1, a map that considers fuel consumption, emission, etc. (during normal control) ) Is a control for adjusting the EGR valve opening and the VN opening. The throttle opening is set to a constant opening (for example, “fully open”) after warming up.

  When the determination result in step ST104 is affirmative (YES), the EGR valve opening, VN opening, and throttle opening for removing from the spatial resonance area Ra are calculated (step ST105). A specific example will be described.

  First, the EGR valve opening is calculated using the map shown in FIG. The EGR valve opening map in FIG. 12 is a map of values (EGR valve opening: Vegra) adapted by experiments and simulations, taking into account emissions and the like, with the engine speed Ne and the accelerator opening Acc as parameters. This is stored in the ROM 202 of the ECU 200. Each value (Vegra) in the map of FIG. 12 is a value closer to the closing side than the map at the time of normal control, and is set as small as possible within a range in which appropriate emission can be secured.

  Regarding the VN opening, the EGR valve opening (predetermined value on the closing side) is determined by the above calculation, and is set to the closing side as much as possible in consideration of drivability and the like. The VN opening may be calculated using a VN opening map using the engine speed Ne and the accelerator opening Acc as parameters, as in the above-described calculation of the EGR valve opening.

  The throttle opening may be set to the same value as in normal control (for example, “fully open”). In addition, as described above, since both the EGR valve opening and the VN opening are set to the close side, considering that the boost pressure may become excessive due to the increase in the turbo rotational speed, the excessive boost pressure is considered. You may set it as the opening which can restrict | limit (guard) a raise (opening of the closing side).

  Next, in step ST106, each drive of the EGR valve 54 and the electric motor 141 of the VN controller 140 based on the EGR valve opening and the VN opening (including the throttle opening in some cases) obtained in step ST105 ( In some cases, the driving of the throttle motor 60 may be included), and the EGR valve opening degree and the VN opening degree are changed to the closed side, thereby increasing the VN passage flow velocity as compared with the normal control.

  In step ST107, it is determined whether or not an elapsed time after changing the EGR valve opening and the VN opening to the closed side has reached a predetermined time Δt. This predetermined time Δt passes through the sections A to B of the spatial resonance area Ra shown in FIG. 9 when the VN passage flow velocity during acceleration is greater than that during normal control (when the passage time of the spatial resonance area Ra is shortened). Is a time required for this, and a suitable value (for example, 0.5 sec) is set by experiment / simulation.

  If the elapsed time after changing the EGR valve opening and the VN opening to the closed side has not reached the predetermined time Δt and the determination result in step ST107 is negative (NO), this elapsed time Wait until the predetermined time Δt is reached. Then, when the determination result in step ST107 is affirmative (YES), that is, when the elapsed time after changing the EGR valve opening and the VN opening to the closed side reaches a predetermined time Δt, the EGR valve The opening degree and the VN opening degree (which may include the throttle opening degree) are returned to the opening degree for normal control, that is, the opening degree for securing the target boost pressure (step ST108).

  As described above, according to the control of this example, when the VN passage flow velocity reaches the flow velocity (vna) of the spatial resonance region Ra during acceleration of the engine 1, the EGR valve opening and the VN opening are closed. Since the VN passage flow velocity is made larger than that during normal control by changing (including changing the throttle opening), the flow velocity through the spatial resonance area Ra, that is, the flow velocity vnb at the point B shown in FIG. It can shift and can pass through spatial resonance area Ra (A-B section shown in Drawing 9) in a short time.

  As a result, the time during which the frequency of the pressure pulsation generated at the rear end of the nozzle vane 121 is amplified in the spatial resonance region can be shortened, and the generation of abnormal noise due to the pressure pulsation can be suppressed. Moreover, since it is only necessary to change the EGR valve opening and the VN opening to the closed side for a short time while passing through the spatial resonance area Ra in the acceleration process, while ensuring the required supercharging pressure (air amount), Generation of abnormal noise due to pressure pulsation can be suppressed.

  In the control of this example, the timing for returning to the normal control after passing through the spatial resonance area Ra is managed by the time Δt. However, it has passed through the spatial resonance area Ra (the point B shown in FIG. 9 has been reached). ) To return to normal control.

  Here, in the control shown in FIG. 10 described above, when the engine 1 is accelerated, the VN passage flow velocity (estimated value) reaches the flow velocity vna (flow velocity at point A in FIG. 9) that enters the spatial resonance region Ra. Although control is performed to increase the passage flow velocity, control is performed to increase the VN passage flow velocity when the frequency of the pressure pulsation proportional to the VN passage flow velocity reaches a frequency that enters the spatial resonance region Ra when the engine 1 is accelerated. You may make it perform.

  In this case, when the engine 1 is accelerated, the VN passage flow velocity is estimated by the same process as step ST103 in FIG. 10, and the Rankine vortex theoretical formula [f = St * U / D] is used by using the estimated VN passage flow velocity. ], The frequency of pressure pulsation is calculated sequentially. Then, when the frequency (calculated value) of the pressure pulsation reaches a frequency that falls within the spatial resonance region Ra shown in FIG. 9, for example, each drive of the electric motor 141 of the EGR valve 54 and the VN controller 140 is controlled, By changing the EGR valve opening degree and the VN opening degree to the closed side, the VN passage flow velocity may be controlled to be larger than that during normal control.

  In this case as well, the VN passage flow rate is normally controlled (control for ensuring the target supercharging pressure) from when the pressure pulsation frequency reaches the frequency that enters the spatial resonance region Ra until a predetermined time Δt elapses. ), The control to be larger than the time may be continued, and the control may be returned to the normal control when Δt has elapsed for a predetermined time.

<VN passage flow rate control during deceleration>
Next, the VN passage flow rate control at the time of deceleration will be described with reference to the flowchart of FIG. The control routine of FIG. 11 is repeatedly executed in the ECU 200 every predetermined time (for example, every several msec).

  First, in step ST201, it is determined whether or not the engine 1 is decelerating. If the determination result is negative (NO), the process returns. If the determination result in step ST201 is affirmative (YES) (when decelerating), the process proceeds to step ST202. In step ST201, when the accelerator is OFF (the accelerator opening obtained from the output signal of the accelerator opening sensor 27 is “0”), it is determined that the vehicle is decelerating.

  In step ST202, the flow velocity vnb (flow velocity at point B in FIG. 9) on the upper limit side of the spatial resonance area Ra described above is read.

  Next, the VN passage flow velocity is estimated in step ST203. Specifically, the parameters relating to the flow rate of exhaust gas toward the turbine wheel 101 (nozzle vane 121) of the turbocharger 100 are the supercharging pressure (air amount), intake air temperature, throttle opening, EGR valve opening, and Based on the VN opening, the VN passage flow velocity is estimated using an estimation map previously adapted by experiments, simulations, or the like. Here, among the parameters used for VN passage flow velocity estimation, the supercharging pressure and the intake air temperature are calculated from the output signals of the intake manifold pressure sensor (supercharging pressure sensor) 28 and the intake air temperature sensor 23, respectively. Further, the throttle opening, the EGR valve opening, and the VN opening are all obtained from a command value (required value). Since the fuel is cut during deceleration (when the accelerator is OFF), the fuel injection amount (combustion gas amount) = 0 is handled in the VN passage flow velocity estimation process in step ST203.

  The VN passage flow rate estimation process in step ST203 is repeatedly performed at predetermined time intervals (for example, several milliseconds) until the determination result in step ST204 becomes affirmative (YES). That is, the estimated value of the VN passage flow velocity is sequentially updated.

  Next, in step ST204, it is determined whether or not the estimated VN passage flow velocity estimated in step ST203 has reached the upper limit flow velocity vnb (flow velocity at point B in FIG. 9) of the spatial resonance region Ra. If the determination result is negative (NO), normal control is continued (step ST208). Here, the normal control is a control for ensuring the target boost pressure (air amount), for example, based on the current operating state of the engine 1, a map that considers fuel consumption, emission, etc. (during normal control) ) Is a control for adjusting the EGR valve opening and the VN opening. The throttle opening is set to a constant opening (for example, “fully open”) after warming up.

  When the determination result in step ST204 is affirmative (YES), the EGR valve opening, VN opening, and throttle opening for removing from the spatial resonance area Ra are calculated (step ST205). A specific example will be described.

  First, the EGR valve opening is calculated using the map shown in FIG. The EGR valve opening map in FIG. 13 is a map of values (EGR valve opening: Vegrb) adapted by experiments and simulations, etc. in consideration of emissions, etc., using the engine speed Ne and the accelerator opening Acc as parameters. This is stored in the ROM 202 of the ECU 200. Each value (Vegrb) in the map of FIG. 13 is a value on the open side of the map at the time of normal control, and is set as large as possible within a range in which appropriate emission can be secured.

  As for the VN opening, the EGR valve opening (predetermined value on the opening side) is determined by the above calculation, and is set to the opening side as much as possible in consideration of drivability and the like. The VN opening may be calculated using a VN opening map using the engine speed Ne and the accelerator opening Acc as parameters, as in the above-described calculation of the EGR valve opening.

  In the case of deceleration, the throttle opening is set to the same value as in normal control (for example, “fully open”).

  Next, in step ST206, the driving of the EGR valve 54 and the electric motor 141 of the VN controller 140 is controlled based on the EGR valve opening and VN opening obtained in step ST205, and the EGR valve opening and VN opening are controlled. By changing the degree to the open side than during normal control, the VN passage flow velocity is made smaller than during normal control.

  In step ST207, it is determined whether or not an elapsed time after changing the EGR valve opening and the VN opening to the open side has reached a predetermined time Δt. This predetermined time Δt passes through the sections B to A of the spatial resonance area Ra shown in FIG. 9 when the VN passage flow velocity is made smaller than that during normal control during deceleration (when the passage time of the spatial resonance area Ra is shortened). This is a time required for the operation, and a suitable value (for example, 0.5 sec) is set by experiment / simulation.

  If the elapsed time after changing the EGR valve opening and the VN opening to the open side has not reached the predetermined time Δt and the determination result in step ST207 is negative (NO), this elapsed time Wait until the predetermined time Δt is reached. Then, when the determination result in step ST207 is affirmative (YES), that is, when the elapsed time after changing the EGR valve opening and the VN opening to the open side reaches a predetermined time Δt, the EGR valve The opening and the VN opening are returned to the opening during normal control (step ST208).

  As described above, according to the control of this example, when the VN passage flow velocity reaches the flow velocity (vnb) of the spatial resonance area Ra when the engine 1 is decelerated, the EGR valve opening and the VN opening are opened to the open side. Since the VN passage flow velocity is changed to be smaller than that during normal control, it is possible to quickly shift to the flow velocity that passes through the spatial resonance area Ra, that is, the flow velocity vna at the point A in FIG. B-A section shown) can be passed in a short time.

  As a result, the time during which the frequency of the pressure pulsation generated at the rear end of the nozzle vane 121 is amplified in the spatial resonance region can be shortened, and the generation of abnormal noise due to the pressure pulsation can be suppressed. In addition, the EGR valve opening and the VN opening need only be changed to the open side for a short period of time while passing through the spatial resonance region in the deceleration process. Generation of abnormal noise due to pulsation can be suppressed.

  In the control of this example, the timing for returning to the normal control after passing through the spatial resonance area Ra is managed by the time Δt. However, it has passed through the spatial resonance area Ra (the point A shown in FIG. 9 has been reached). ) To return to normal control.

  Here, in the control shown in FIG. 11 described above, when the VN passage flow velocity (estimated value) reaches the flow velocity vnb (the flow velocity at the point B in FIG. 9) that enters the spatial resonance area Ra when the engine 1 is decelerated. Although control is performed to reduce the passage flow velocity, control is performed to reduce the VN passage flow velocity when the frequency of the pressure pulsation proportional to the VN passage flow velocity reaches a frequency that enters the spatial resonance region Ra when the engine 1 is decelerated. You may make it perform.

  In this case, when the engine 1 is decelerated, the VN passage flow velocity is estimated by the same process as step ST203 in FIG. 11, and the Rankine vortex theoretical formula [f = St * U / D] is used by using the estimated VN passage flow velocity. ], The frequency of pressure pulsation is calculated sequentially. Then, when the frequency (calculated value) of the pressure pulsation reaches a frequency that falls within the spatial resonance region Ra shown in FIG. 9, for example, each drive of the electric motor 141 of the EGR valve 54 and the VN controller 140 is controlled, By changing the EGR valve opening and the VN opening to the open side, the VN passage flow velocity may be controlled to be smaller than that during normal control.

  In this case as well, the VN passage flow rate is normally controlled (control for ensuring the target supercharging pressure) from when the pressure pulsation frequency reaches the frequency that enters the spatial resonance region Ra until a predetermined time Δt elapses. The control to be smaller than that at the time may be continued, and the control may be returned to the normal control when Δt has elapsed for a predetermined time.

<Other VN flow velocity control during acceleration / deceleration>
Next, another example of VN passage flow rate control during acceleration and deceleration will be described below.

  (I) An experiment or the like is performed on the actual engine 1 of the target engine, and the operating conditions (engine rotation speed Ne, load (accelerator opening) where the VN passage flow velocity (pressure pulsation frequency) enters the spatial resonance region Ra shown in FIG. Degree Acc) and the gear stage of the transmission).

  (Ii) When the engine 1 accelerates, when the operating condition enters the spatial resonance area Ra, the EGR valve opening, the VN opening, and the throttle opening for realizing the VN passage flow velocity for removing from the spatial resonance area Ra. The VN passage flow velocity calculation map is created by adapting each opening degree (the opening degree on the closing side with respect to the normal control) by experiments and simulations.

  (Iii) EGR valve opening degree, VN opening degree, throttle opening degree that realizes a VN passing flow velocity for removing from the spatial resonance area Ra when the operating condition enters the spatial resonance area Ra when the engine 1 is decelerated The VN passage flow velocity calculation map is prepared by adapting each opening degree (opening side opening degree from the normal control time) by experiments and simulations.

  When the engine 1 is accelerated, when the actual operating state (engine speed Ne, load (accelerator opening Acc), transmission gear stage) reaches the spatial resonance area Ra, the VN passage flow velocity calculation map ( EGR valve opening, VN opening, and throttle opening are calculated on the basis of the acceleration), and the opening of the EGR valve 54 and nozzle vane 121 (electric motor 141), throttle are calculated based on the calculated opening. By controlling the motor 60 so that the VN passage flow velocity is larger than that in the normal control, the spatial resonance region Ra can be passed in a short time.

  When the engine 1 decelerates, when the actual operating state (engine speed Ne, load (accelerator opening Acc), transmission gear stage) enters the spatial resonance region Ra, the VN passage flow velocity calculation map ( EGR valve opening, VN opening, and throttle opening are calculated based on the deceleration), and the EGR valve 54, nozzle vane 121 opening (electric motor 141), throttle are calculated based on the calculated opening. By controlling the motor 60 to make the VN passage flow velocity smaller than that during normal control, the spatial resonance region Ra can be passed in a short time.

  Thus, even in the control of this example, the time during which the frequency of the pressure pulsation generated at the rear end of the nozzle vane is amplified in the spatial resonance region can be shortened, and the generation of noise due to the pressure pulsation can be suppressed. Can do. In addition, the VN passage flow velocity only needs to be changed for a short time while passing through the spatial resonance region during acceleration or deceleration, so that the required supercharging pressure (air amount) is ensured and the difference caused by pressure pulsation is ensured. Generation of sound can be suppressed.

-Other embodiments-
In the above example, the case where the present invention is applied to a common rail in-cylinder direct injection multi-cylinder (four-cylinder) diesel engine has been described. The present invention is not limited to this, and can be applied to a diesel engine having any other number of cylinders such as a six-cylinder diesel engine.

  Moreover, although the example of control of a diesel engine was demonstrated in the above example, this invention is not limited to this, This invention is applicable also to control of the gasoline engine provided with the variable nozzle vane type turbocharger.

  In the above example, the case where the present invention is applied to an internal combustion engine (diesel engine, gasoline engine, etc.) equipped with an EGR device (exhaust gas recirculation device) has been described. However, the present invention is not limited to this, and EGR The present invention can also be applied to control of an internal combustion engine with a supercharger (an engine with a variable nozzle vane turbocharger) that is not equipped with a device.

  In the present invention, as an actuator for driving the variable nozzle vane mechanism, for example, a negative pressure type or a hydraulic type actuator may be used in addition to a motor type actuator using an electric motor as a drive source.

  INDUSTRIAL APPLICABILITY The present invention can be used for control of an internal combustion engine (engine) equipped with a variable nozzle vane supercharger, and more specifically, can be effectively used for control for suppressing abnormal noise caused by pressure pulsation generated at the nozzle vane rear end. can do.

DESCRIPTION OF SYMBOLS 1 Engine 11 Intake passage 12 Exhaust passage 5 EGR apparatus 54 EGR valve 6 Throttle valve 60 Throttle motor 23 Intake temperature sensor 25 Engine speed sensor 26 Throttle opening sensor 27 Accelerator opening sensor 28 In manifold sensor (supercharging pressure sensor)
100 Turbocharger (Variable nozzle vane type turbocharger)
DESCRIPTION OF SYMBOLS 101 Turbine wheel 102 Compressor impeller 120 Variable nozzle vane mechanism 121 Nozzle vane 140 VN actuator 141 Electric motor 200 ECU

Claims (12)

A throttle valve arranged in the intake passage;
The compressor impeller provided in the intake passage, the turbine wheel provided in the exhaust passage, and a plurality of nozzle vanes provided on the outer peripheral side of the turbine wheel, and exhaust gas by changing the opening degree of the nozzle vane A supercharger comprising a variable nozzle vane mechanism for adjusting the flow of
An EGR valve that is provided in an EGR passage that connects an exhaust passage upstream of the turbine wheel and an intake passage downstream of the compressor impeller, and adjusts the amount of exhaust gas that circulates from the exhaust passage to the intake passage. When,
A catalyst provided in an exhaust passage on the downstream side of the turbine housing of the supercharger;
In a control device for an internal combustion engine with a supercharger comprising:
When accelerating or decelerating, when the flow velocity of the exhaust gas that passes through the nozzle vane reaches the flow velocity that enters the spatial resonance region in the exhaust gas passage space from the turbine housing of the turbocharger to the catalyst, it passes through the nozzle vane. One or more of the opening of the throttle valve, the opening of the EGR valve, and the opening of the nozzle vane are adjusted so that the flow rate of the exhaust gas becomes a flow rate outside the spatial resonance region. A control device for an internal combustion engine with a supercharger, characterized by further comprising a flow rate control means for controlling the flow rate of the exhaust gas passing through the nozzle vane. The control device for an internal combustion engine with a supercharger according to claim 1,
The flow rate control means adjusts the flow rate of the exhaust gas passing through the nozzle vane to a boost pressure, an intake air temperature, a fuel injection amount, an opening of the throttle valve, an opening of the EGR valve, and an opening of the nozzle vane. When the estimated flow velocity reaches a flow velocity that enters the spatial resonance region, the throttle valve is opened so that the flow velocity of the exhaust gas that passes through the nozzle vane becomes a flow velocity outside the spatial resonance region. A control device for an internal combustion engine with a supercharger, which controls any one or more of the opening degree of the EGR valve and the opening degree of the nozzle vane. The control apparatus for an internal combustion engine with a supercharger according to claim 1 or 2,
The flow rate control means is configured to open the throttle valve, the EGR valve, and the nozzle vane when the flow rate of the exhaust gas passing through the nozzle vane reaches a flow rate that enters the spatial resonance region during acceleration. A control device for an internal combustion engine with a supercharger, wherein the flow rate of exhaust gas passing through the nozzle vanes is increased by controlling any one or a plurality of degrees of opening. The control apparatus for an internal combustion engine with a supercharger according to claim 3,
The flow rate of the exhaust gas passing through the nozzle vane is increased by setting the opening of the EGR valve to a predetermined value on the closing side and controlling the opening of the nozzle vane to the closing side. Control device for an internal combustion engine with a feeder. The control apparatus for an internal combustion engine with a supercharger according to claim 3 or 4,
An internal combustion engine with a supercharger, wherein an increase in supercharging pressure is limited by adjusting an opening of the throttle valve while a flow rate of exhaust gas passing through the nozzle vane is a flow rate in the spatial resonance region. Control device. The control device for an internal combustion engine with a supercharger according to claim 3, 4 or 5,
During acceleration, the control for increasing the flow rate of the exhaust gas passing through the nozzle vane is continued until a predetermined time elapses after the flow rate of the exhaust gas passing through the nozzle vane reaches the flow rate entering the spatial resonance region. A control apparatus for an internal combustion engine with a supercharger. The control apparatus for an internal combustion engine with a supercharger according to claim 1 or 2,
The flow rate control means, when decelerating, when the flow rate of exhaust gas passing through the nozzle vane reaches a flow rate that enters the spatial resonance region, the opening degree of the throttle valve, the opening degree of the EGR valve, and the opening of the nozzle vane. A control apparatus for an internal combustion engine with a supercharger, wherein the flow rate of exhaust gas passing through the nozzle vane is reduced by controlling any one or a plurality of degrees of opening. The control device for an internal combustion engine with a supercharger according to claim 7,
The flow rate of the exhaust gas passing through the nozzle vane is reduced by setting the opening of the EGR valve to a predetermined value on the opening side and then controlling the opening of the nozzle vane to the opening side. Control device for an internal combustion engine with a feeder. The control device for an internal combustion engine with a supercharger according to claim 7 or 8,
During deceleration, control is performed to reduce the flow rate of the exhaust gas passing through the nozzle vane until a predetermined time elapses after the flow rate of the exhaust gas passing through the nozzle vane reaches the flow rate entering the spatial resonance region. A control apparatus for an internal combustion engine with a supercharger. A throttle valve arranged in the intake passage;
The compressor impeller provided in the intake passage, the turbine wheel provided in the exhaust passage, and a plurality of nozzle vanes provided on the outer peripheral side of the turbine wheel, and exhaust gas by changing the opening degree of the nozzle vane A supercharger comprising a variable nozzle vane mechanism for adjusting the flow of
An EGR valve that is provided in an EGR passage that connects an exhaust passage upstream of the turbine wheel and an intake passage downstream of the compressor impeller, and that adjusts the amount of exhaust gas that circulates from the exhaust passage to the intake passage. When,
A catalyst provided in an exhaust passage on the downstream side of the turbine housing of the supercharger;
In a control device for an internal combustion engine with a supercharger comprising:
When accelerating or decelerating, the frequency of pressure pulsation proportional to the flow rate of exhaust gas passing through the nozzle vane reaches a frequency that enters a spatial resonance region in the exhaust gas passage space from the turbine housing of the turbocharger to the catalyst. And adjusting one or more of the opening of the throttle valve, the opening of the EGR valve, and the opening of the nozzle vane so that the pressure pulsation frequency deviates from the spatial resonance region. A control device for an internal combustion engine with a supercharger, characterized by comprising flow rate control means for controlling the flow rate of exhaust gas passing through a nozzle vane. A throttle valve arranged in the intake passage;
The compressor impeller provided in the intake passage, the turbine wheel provided in the exhaust passage, and a plurality of nozzle vanes provided on the outer peripheral side of the turbine wheel, and exhaust gas by changing the opening degree of the nozzle vane A supercharger comprising a variable nozzle vane mechanism for adjusting the flow of
A catalyst provided in an exhaust passage on the downstream side of the turbine housing of the supercharger;
In a control device for an internal combustion engine with a supercharger comprising:
When accelerating or decelerating, when the flow velocity of the exhaust gas that passes through the nozzle vane reaches the flow velocity that enters the spatial resonance region in the exhaust gas passage space from the turbine housing of the turbocharger to the catalyst, it passes through the nozzle vane. Exhaust gas that passes through the nozzle vane by adjusting one or both of the opening degree of the throttle valve and the opening degree of the nozzle vane so that the flow rate of the exhaust gas becomes a flow rate outside the spatial resonance region A control device for an internal combustion engine with a supercharger, characterized in that it comprises flow rate control means for controlling the flow rate of the engine. A throttle valve arranged in the intake passage;
The compressor impeller provided in the intake passage, the turbine wheel provided in the exhaust passage, and a plurality of nozzle vanes provided on the outer peripheral side of the turbine wheel, and exhaust gas by changing the opening degree of the nozzle vane A supercharger comprising a variable nozzle vane mechanism for adjusting the flow of
A catalyst provided in an exhaust passage on the downstream side of the turbine housing of the supercharger;
In a control device for an internal combustion engine with a supercharger comprising:
When accelerating or decelerating, the frequency of pressure pulsation proportional to the flow rate of exhaust gas passing through the nozzle vane reaches a frequency that enters a spatial resonance region in the exhaust gas passage space from the turbine housing of the turbocharger to the catalyst. Further, the flow rate of the exhaust gas passing through the nozzle vane by adjusting one or both of the opening degree of the throttle valve and the opening degree of the nozzle vane so that the pressure pulsation frequency deviates from the spatial resonance region. A control device for an internal combustion engine with a supercharger, characterized by comprising a flow rate control means for controlling the engine.

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